Flash line, light band and insufficient filling are the main defects in coining process for Au-Ag commemorative coins. Based on a special-purpose FEM software-COINFORM, numerical simulations for coinages were carried out. A radial friction power model was built for the prediction of light band defects. With the analysis of metal flow, the mechanism of flash line was studied on the basis of the experimental results. The former algorithm was improved that the simulation would stop only when the blank was fully contacted with the forming tools in all direction. The reaction force of blank at the stop time predicts the forming force in coining. Experimental results show that the predicted force is valid for eliminating insufficient filling.

闪光线、光亮带和压印不足是金银纪念币压印成形中的主要缺陷。基于实验室研发的压印成形模拟系统COINFORM,对纪念币的压印过程进行了数值模拟。在对光亮带缺陷分析的基础上,建立了径向摩擦功模型预测光亮带的位置。结合实验结果和成形模拟中金属的流动情况,分析了闪光线的形成机理。将原有算法进行改进,根据计算过程中坯饼表面和模具的接触状态确定结束计算时刻,并以计算结束时的坯饼反作用力来预测实际成形时所需的压印力。实验结果表明,所预测的压印力对压印不足缺陷的消除是有效的。

金银纪念币, 压印成形, 缺陷预测, COINFORM